1. Field of the Invention
The present invention generally relates to the testing of integrated circuit devices, and more particularly to a handler contact checking device which can detect a contact failure between handler pins and terminals of the IC devices to be tested, and to a testing method using the handler contact checking device.
2. Description of the Related Arts
In general, integrated circuit devices are obtained by integrating multiple circuit elements into a single semiconductor substrate and then packaging the elements so as to provide electrical connection terminals and to protect the circuit elements from a hostile external environment. All of the packaged IC devices must be tested before shipment to verify that the IC devices exhibit the intended normal functions specified during the initial circuit design. In the testing process, a test system applies test signals to the IC devices to be tested and measures output signals from the IC devices. The term "test system" commonly refers to the combination of the hardware (test apparatus) for supplying the test signal and measuring the output signal, and the software (test program) for instructing and controlling the operations of the hardware.
Handling of the IC devices is carried out by a handler which automates the loading of devices to be tested, the fixing of IC devices under test, and the sorting of the tested devices. Signal communication between the test system and the IC devices is accomplished through the handler, and the handler has a number of pins directly contacting terminals of the IC devices. Accordingly, when the contacts are not accurately aligned, the signal communication between the test system and the IC devices becomes poor, and a normally functional IC device may incorrectly be sorted as a defective device. This in turn reduces the production yield of the test operation.
FIG. 1 is a failure management flow chart according to the prior art and describes the situation when contact failures between a handler and an IC device have occurred. In the start step 10, a test apparatus is set up in a stable state for actual testing operations. Next, a handler is set up in step 12, for example, by mounting a test board to provide signal communication between the test apparatus and the IC device. In preliminary test step 14, one IC device is loaded into the handler and a preliminary test is conducted according to a test program. The results of the preliminary test are analyzed to check the operating state or connection of the handler. If the handler is determined to be in a normal operating state, the test apparatus starts the actual testing of the IC devices by providing test signals in step 15. However, if the handler is in an abnormal operating state, the operator must determine the cause of the failure in step 16. If the handler failure is found to be a handler contact failure (step 17), the operator or engineer takes a proper action to correct the problem in step 18. The process flow 19 then returns to the handler contact preliminary test step 14, and repeats the steps described above. The failures found during the handler contact preliminary test may result from various causes, including functional errors in the handler itself, failures in test board connections or wiring circuits, and mis-mounting of the test board on the handler.
The above described prior art suffers some drawbacks. It is difficult to determine an optimal contact between the handler and the IC devices prior to the actual test. Further, when a handler contact failure is found, the contact located within the handler cannot be visually inspected and a proper checking tool is not available. Therefore, in order to remedy the contact failure, the test apparatus must be stopped prior to checking the handler contact. This increases the set up time of the test apparatus and the handler, which degrades the production yield of the IC devices.